Untitled

#include<iostream> 

using namespace std; 

int main(){ 
	long long int a, b; 
	cin >> a >> b;  
	long long int  sum = 0;
	for(long long int i = a; i <= b; i++){ 
		if(i % 2 != 0){ 
			sum += i;
		}
	} 
	cout << sum;


}